From Seven 20. This Harry Potter Heat Reveal Mug features the iconic image of Harry, Ron and Hermione from Harry Potter and the Deathly Hallowsmotion picture. The mug features a solid blue exterior that reveals the image when a hot beverage is added. Heat reveal works with coffee, hot chocolate, or any warm beverage (including hot Butterbeer) No wand necessary! Ceramic. 20 oz. Mug measures: 5" x 5" x 6".